In recent years, the development of digital cameras has been progressed rapidly, so that the digital cameras have become one of the most indispensable parts of our daily life. Therefore, enhancing the image quality has always been one of the essential topics in the industry fields. In brief, photography is utilized light to irradiate on an object, and after the light is reflected and passed though a lens of a digital camera, an image processing is subsequently performed inside the digital camera. However, the light can further include a non-visible light such as an infrared (IR) light or an ultraviolet light besides the visible light. The current techniques are mostly employed optical filters to filter out the infrared light or adjust the light entering the inside of the digital camera.
FIG. 1 is a schematic diagram illustrating an existing image sensor which receives light and a color filter array thereof in a digital camera. Referring to FIG. 1, the image sensor 10 includes a lens 110, a color filter array 120 and a sensor chip 130, in which the color filter array 120 is formed by a plurality of sub-pixel arrays arranged in an array. For example, the sub-pixel array 122 is arranged in Bayer pattern. Moreover, an infrared cut filter 20 is further included, and is disposed above the image sensor 10.
Generally speaking, the infrared cut filter 20 has to be used to filter out the infrared light when a sufficient light source is provided. If the image sensor 10 receives an infrared signal, the image processing such as performing color calculation and automatic white balance (AWB) can be easily interfered by the infrared signal and the errors are caused in the calculation, so that there is a great difference between the color appeared form the image and the color seen by human eyes. However, the image sensor 10 can only increase the brightness through a flash lamp when an insufficient light source is provided, but the effect from the flash lamp tends to cause an unnatural feeling to the user with regard to the image quality.